It is Illegal, In England at least. I do not think it is morally wrong but it is lawfully wrong.

In England The Communications Act of 2003 states "a person who (a) dishonestly obtains an electronic communications service, and (b) does so with intent to avoid payment of a charge applicable to the provision of that service, is guilty of an offence".

I'm sure there is a similar, if not the same law in place in the good ol' USA.

Sorry to tell you that your theory is completely wrong, that neighbor might not have any clue about WiFi security, nor it's public. So by using it you're slowing the connection down(in case they had a slow connection), you're joining a personal network which might have some personal objects(Pictures,music, videos).Here is an example to get you close to your theory, would you use your neighbor's hose to wash your car when your neighbor is going to pay the monthly bills.

Well, let's see. They chose to not secure their wi-fi network. If they didn't know how to secure it, why would I join it anyways, because it would most-likely be slow (unless it's public wi-fi which is never as fast as your home connection).

If I were to use their hose to wash my car, I would be stealing physical property. Would it be wrong if I stood on my side of my property and extended a vacuum hose over to their side and "steal their air?"

Stealing wi-fi is a morality issue, and I don't think that it is fully applicable to law.

I'm going to say no. If I leave my door unlocked, is it legal for you to walk in, and use my stuff? Yes, it may be my fault, but that doesn't change your intent. You are stealing, plain and simple...In my mind, the key word here is "intent"

Technically, using someone's wi-fi without their permission is stealing and can be prosecuted. However, in my opinion, it's like arguing breaking & entering when the door isn't locked and the robber isn't armed. Even worse, you can barely prove the wi-fi was stolen. Sure, you can go off and list a few ways to detect the packets etc, but the permission part comes down to he said she said.

Really? Whenever I go to a store,the door is opened and unlocked. Does that mean I can just walk in and take whatever I want? What about after it's closed, and the owner forgets to lock the door? Does that make it ok?

This really is a unknown thing. I have never heard a story of someone being arrested for using someones open wi-fi. However, it is stealing because the owner is paying for the internet and you are using what they are paying for for free. However some will argue that it is not costing them more money, which is true.

Look at it this way: Lets say that you leave your car doors unlocked with the keys on the seat for whatever reason it is illegal from someone to come up and take your car and drive away even though you have left it open.

There are just too many "ifs" so it really is just better to not use it if you can use your own.

I am not going to deny that I have not taken advantage of open wi-fi before on my iPod because I have. But I still say that it is stealing.